


The Seventh Crusade

by undisputedbitch



Category: Harry Potter - J. K. Rowling
Genre: F/F
Language: English
Status: Completed
Published: 2021-02-10
Updated: 2021-02-10
Packaged: 2021-03-12 20:48:23
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings, Graphic Depictions Of Violence, Major Character Death, Underage
Chapters: 3
Words: 4,402
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29890335
Author URL: https://archiveofourown.org/users/undisputedbitch/pseuds/undisputedbitch
Summary: As the oldest son of one of the last remaining pureblood families, you're expected to do things you don't want to protect your family, even if it means killing the girl you love.
Relationships: Theodore Nott/Original Character(s)
Kudos: 1





	1. Prologue

**Author's Note:**

> Previously known to many as “ETERNALLY PURE,” but I’ve recently changed the title. Still a work in progress, I’m afraid, and it's currently being translated into Spanish. Keep in mind that this version is extremely different from the Wattpad version.

_**Summer, 1997** _

With purple lips and chattering teeth, the young witch gripped her wand tightly, hoping to gain comfort that she knew would never come. Her pulse quickened, and blood surged through her veins as she fought to catch her breath.

The biting chill filled her lungs with every breath of stale air, creating thick clouds of white mist. Her grey eyes followed the smoke upwards towards the walking skeleton making his way to the top of the Astronomy Tower. 

The sun had set, yet she knew from the sight of his chestnut hair and opulent suit - it was him. 

"Good evening Theodore.” A familiar voice called from the opposite end of the tower. 

Dumbledore.

Cassia’s eyes wandered back to the dark-haired boy, and suddenly an overwhelming sense of guilt washed over her. He looked dreadful, and she had no one to blame but herself. For months, she'd been so preoccupied with her own endeavors that she failed to see just how much he had deteriorated over the short period of time. 

_Oh, you stupid boy. What have you done?_

Gone was Theodore Nott, the quiet boy who preferred to keep to himself, and in his stead stood a frightened young man. A man who still possessed Cassia's heart - despite everything he put her through. 

Theo stood poised and strong, with his wand raised - aiming itself at the Hogwarts headmaster. His eyes darted about the room in search of anyone who would sort out Dumbledore, anyone who would have followed the pair. 

"Who else is here?" His voice trembled. "I heard you talking."

Cassia's eyes flickered over towards Harry, who stood beside her, his eyes still fixated on the conversation above. Harry broke away from his trance and slinked about silently, trying to get a better view of their encounter.

"I often speak aloud to myself," Dumbledore replied calmly, without any ease. "I find it extraordinarily useful. That which sounds sane at a whisper can seem utterly mad when said for all the world to hear. Haven't been whispering to yourself, have you, Theodore?”

Please don't do this, Nott. Please. Cassia pleaded to him silently.

Theo’s eyes continued to dance about the room, seeming unconvinced. Theo knew Dumbledore wasn't alone. He knew _she_ was around there somewhere - she was never too far away. It was one of the very few things that he hated about her; her knack for lurking in the shadows.

"You are not an assassin Theodore.”

Theo scowled back at the grey-haired wizard, his wand getting higher, "How do you know what I am? I've done things that would shock you."

"Like cursing Miss McKinnon and hoping she would, in turn, bear a cursed necklace to me? Like replacing a bottle of mead with one laced with poison? Forgive me, Theodore, but these attempts are so feeble. It would seem you only succeeded in hurting one particular person consistently, in my stead."

The raven-haired girl watched from below as her lover’s cold eyes softened at Dumbledores words. Her heart began to race once again. In all their time together, Theo was never very good at expressing himself - especially when it came to her. However, just at the mere mention of her name, even she could see his thick walls begin to crumble. If only she could reach him in time. 

Theo's brow quivered slightly. "Where is she?"

"And who might you be referring to?"

"You know who! Where is she? Where's McKinnon? I know she's around here somewhere. She has to be. She's always sticking her nose in places it doesn't belong." Theo growled. His voice getting louder and wand getting higher with every passing second.

"Ah," Dumbledore replied, slowly creeping closer to Theo. "I would hope Cassiopeia is off somewhere, doing good just as I've instructed her to do. I must say, she is an exceptionally gifted young witch. You mustn't underestimate her, Theodore; she may be stronger than you realize."

With hope, Cassia's eyes darted back to Theo, who had not yet lowered his wand. Admittedly, she knew he was no stranger to hexing - but killing; it just wasn't in his nature. Although, she be so sure anymore. With just a single look in his eyes, she could tell that he was desperate. However, if there was one thing that Cassia was certain of, it was that he would go to the ends of the earth to protect the ones he loves.

Even if that meant killing. 

Cassia followed Theo’s gaze as Dumbledore began to slowly and, without intent, draw his wand, "I shall make it easy for you then."

" _Expelliarmus_!"

Together, Cassia and Harry observed silently from below, baffled as Dumbledore's wand flew through the cold air before cluttering across the grid above their heads.They stared at each for a moment before redirecting their attention back to Theo, whose eyes had a mixture of fear and awe inside of them.

Cassia’s eyes widened as Harry began to draw his own wand, thrusting it high and pointing it in the direction of Theo. Cassia's grip on her own wand tightened while her mind raced, with a million different thoughts running through her head. If things ended badly, if it came down to Harry or Theo, she wasn't entirely sure which one she would choose. The grip on her wand began to loosen, knowing exactly who she would choose. 

She'd already made her choice a long time ago.

"Well done, Theodore,” Dumbledore praised from above, half-heartedly, “Well done. But I warn you. Killing is not nearly as easy."

Harry's head whipped away from Theo and towards the entrance as the sound of heavy footsteps echoed throughout the tower. Theo gazed into Dumbledore's eyes then to the sky, at the gathering clouds, twisting darkly.

"You're not alone. Are you. There are others. How?"

"The vanishing cabinet in the Room of Requirement. Malfoy and I have been mending it for weeks, and none of you idiots ever knew.” Theo sneered viciously.

"Let me guess," Dumbledore interrupted, sounding more fascinated than fearful, "it has a sister - a twin."

"In Borgin & Burkes. They form a passage."

"Ingenious. Theodore,” Dumbledore, again attempted to slowly creep forward, "Years ago I knew a boy who made all the wrong choices. He not only succeeded in destroying himself - but everyone around him as well. I do not wish for you to repeat those same mistakes. Please let me help you."

"I don't want your fucking help!" The boy cried out in terror. "Don't you understand? I have to do this. I have to kill you. O-or… He’ll kill her.”

 _Damn you, you idiot boy_.

Her head whipped towards the stairwell as dozens of death eaters began to climb the tower, making their way towards the grey-bearded Professor and dark-haired boy. At the head of the pack stood Cassia's malevolent aunt, Bellatrix.

The woman who murdered her father.

The young girl raised her own wand this time, aiming it mercilessly at the mad witch. She knew the spell and the consequences that went along with it. But it was just there, hanging on the tip of her tongue, just waiting to be said. And suddenly, the darkness had swept over her once again. 

_Do it. You know the spell._ Said the voices in her head.

But she couldn't, not yet.

Her mind had been so consumed with revenge and concern for her young love that she hadn't noticed Severus Snape - pointing his wand at Harry. Snape had not yet noticed the grey-eyed girl standing there as well, giving her an ounce of hope.

She could still save him.

Cassia watched from the shadows as Harry reluctantly lowered his wand in surrender. She was taken back when Snape didn't attempt to hex Harry but instead put a finger to his cold lips, commanding her the Chosen One to be silent and still. 

And without any hesitation at all, Cassia took what little opportunity she had left to bypass them both swiftly. Making a mad dash for the stairwell.

"No!" They both cried. But neither man could stop her.

With each step she took, her heart drummed faster and faster, her breath quickening once again. A small lump began to form in the back of her throat as she reached the last step, the entire room coming to a halt at her presence.

“McKinnon?” Theo’s head snapped towards the entrance of the stairwell. "What are you doing here?" He hissed.

"Oh!" Bellatrix exclaimed with delight, clapping her hands with excitement. “Well, if it isn’t my little niece. Just in time for the show. Oh! You're here to stop your boyfriend, aren't you dearest? Well, I'm afraid it's too late for that. No matter, you'll be coming with us." Bellatrix cried out in hysterics.

With wand in hand, Cassia began to raise it slowly, pointing it first at Bellatrix; and then towards Dumbledore.

Flabbergasted, Theo slowly lowered his own wand.

“What are you doing, you idiot?" He hissed to the grey-eyed girl. "Put it down, McKinnon! Put it down! I have to do this. Me! I have to do this, or he'll kill my family. My father. My brother. Sister. Then you..."

"No!" Snape called from behind, taking this opportunity to shove the petite girl out of his way and back towards the stairwell. But it was too late; she was trapped. The death eaters did not attempt to stop Snape; their attention still focused on the small girl.

"Please." Dumbledore pleaded, his eyes shooting to Snape and then to the girl.

She watched as Dumbledore's cold eyes began to water, knowing deep down - it was his time.

" _Avada Kedavra_!"


	2. Sleepless Nights

_**Autumn, 1995**_

No matter how hard she tried, Cassia couldn’t seem to fall asleep.

After hours of tossing and turning, the young girl wanted nothing more than to lay down and surround herself in the warmth of silence, welcoming the much-needed rest - but her mind wouldn’t allow it. There were just too many thoughts swarming around inside her head.

Although completely eloped in darkness, she could hear the gentle tapping against the glass of her bedroom window. Blurry jolts of electricity flashed before her tired eyes, igniting the excitement within.

Fall had arrived at last.

After a never-ending summer heat, the heavens had released a torrent of rain. It was a gift to the parched flora and the animals who grieved over the dry stream beds. Summer had officially been put to rest.

It was enticing, electrifying. Listening to the gentle swish of the trees as they swayed with the now Autumn breeze.

What first began as high winds and light rain had soon built into a scene of chaos. Calamity ensued; the trees writhed and flailed about, carrying their groans of pain with the wind. It screamed rather than howled, like a horde of enraged banshee's, uprooting weeds and shrubs with their fits of ever-consuming fury.

Kicking the covers off and striding towards the ajar window, Cassia held her hand to the cold glass, watching her warm breath condense around her outstretched fingers.

Had it not been for the knock at her bedroom door, she may have still been submersed in her own fantasies. But as fate would have it, the reality was calling.

"Oh good, you’re awake.” Said the slender man, popping his head in from the corridor. “I thought you might be. You know, you never were able to sleep through a storm, not even when you were little. Such a wriggly little tike you were.”

"Only a mad man could sleep through a storm like this, uncle Moony.” She giggled whilst her guardian slipped into the lilac-colored room. "You’re home early. I thought you said you wouldn’t be home for another two days. What happened? Nothing bad, I hope.” 

Remus Lupin’s silhouetted figure approached the young girl, who sat parched in her bay window. Though still quite young, Lupin seemed tired and rather ill-looking; he had more grey hairs and his robes were patched and shabbier than ever. Nevertheless, he was smiling broadly down at Cassia, who tried to smile back despite the swarming thoughts in her head.

“I couldn’t pass up an opportunity to say goodbye, not when we’ll be apart for so long. Although if you must know, there was a slight problem with one of your classmates. It turns out the boy had an unfortunate accident that required the use of magic. But I’m sure Professor Dumbledore will do everything he can to ensure the greatest outcome.” 

"Boy? Which boy?" She asked curiously.

Perhaps it was her uncle’s furrowed brow, or possibly the way he rocked back and forth on the heels of his feet, which made it seem as if the situation were greater than she anticipated. Cassia couldn't be sure. However, judging by his actions, the matter must’ve been grave indeed.

Like a deer in headlights, Lupin replied swiftly. "No one of your concern. Come on, off to bed. Merlin’s beard, you really must get around to cleaning this room - I must say, it’s absolutely atrocious in here, Cassia.”

Her room was certainly much messier than the rest of the house. Alone in the confines of their home for three days, Cassia hadn’t bothered tidying any of it. Most of the books she owned were scattered across the floor, where she tried to distract herself with reading but ended up tossing them all aside. Artemisia’s cage certainly needed a good cleaning as well, as it began to smell. Cassia’s trunk lay open, revealing a pile of unfolded clothing spilling out onto the floor around it.

"Why are you changing the subject?” Asked Cassia, who gradually began picking up the scattered books and throwing them hastily into the trunk. “Could it possibly be so bad that you can’t tell me who it was?”

Lupin swiftly waved his wand in a long, sweeping movement over the floor to assist the girl in her pursuit to tidy. Books, clothing, telescope, and other belongings all soared into the air and flew into the trunk without ease.

"Bed now," Lupin grumbled, now aware that it was well past midnight. 

“But I can’t sleep.” Cassia protested, her eyes drifting back to the window as the lightning flashed once more. “My brain’s all muddled like it’s gone into hyperdrive, and no matter how hard I try - I just can’t shut it off. It’s probably the stress of starting a new year...”

If only that were true.

She hadn’t the heart to tell him the truth, not when he already had so much on his plate. So, Cassia decidedly kept her thoughts to herself - hoping that by some miracle, they would fade away.

"No matter.” Lupin coughed, clearing the bubble in his throat. “I’ll brew you a sleeping potion. Something to help you sleep better through the night. That way, you can actually get a decent night's rest.”

With a strained voice, Cassia whispered. “Thank you, uncle.”

It was times like these Lupin wished his career wasn’t so high in demand. The Advanced Guard were the members of the Order of the Phoenix, entrusted with protecting the most important witches and wizards. Why he didn’t refuse the opportunity to join the Guard when he had the chance was a complete and utter mystery.

Because no one was more important than his god-daughter.

“Listen, I know I’ve been absent quite a lot these last few weeks. But given my current line of work, I’m required to be there when called upon. However, if there is anything I can do to help in any way, I am more than willing to do so. Just say the word, my dear." He murmured, rubbing comforting circles on the small of her back.

"You don’t have to worry about me, uncle Moony. I’m a big girl, and I’m more than capable of taking care of myself." She replied that smile he loved oh so much, finally beginning to creep back onto her face.

"Alright. Well, I know when I'm not wanted." With a final kiss on the top of her head, he retreated from the confines of her new clean bedroom. "Oh. It almost slipped my mind… Fred and George send their regards. Something about concocting a new set of fireworks this year. You wouldn't happen to know anything about that now, would you?"

With a bashful giggle, Cassia replied. “Not a clue.”

"Hm. I'm sure. Well, sweet dreams, my dearest. I will see you bright and early in the morning," He chuckled back, pulling the door shut gently.

"Goodnight."

Once the door had sealed shut behind him, Cassia began fiddling with the shimmering gold band wrapped elegantly around her right index finger. A possession that belonged to her mother.

Tracing the clumsy engravings on the ring with the tips of her fingers, Cassia could only faintly make out a particular symbol. A symbol which, to that day, Cassia hadn’t a single idea of what it meant, nor the significance to her late mother.

A vertical line and circle, enclosed within a triangle. But what did it mean? 


	3. Gryffindor's Princess

It took all but five minutes to reach King’s Cross. Once inside the station, Cassia and Lupin lingered about casually. The Hogwarts Express stood belching sooty steam over the all too familiar platform packed with departing students and their families.

Cassia inhaled the familiar scent, feeling her spirits grow. She was going home.

“Well, look after yourself.” Said Lupin, reaching over and pulling her into a tight hug. “Keep your head up high and try to be discreet about what you put into your letters. I suspect the ministry may be intercepting them. But if at any time you feel like you're in danger, just send me a chocolate bar. I’ll know what it means.”

“Moony...I don't know how I feel about going back. I-I don't think I can go back. Not with everyone staring at me, watching my every move. I think I'll go insane.” Cassia muttered into his chest.

It was a tragedy. A complete and utter tragedy. Barely three months since the accident and Cassia still had trouble sleeping. But she had to go back. Hogwarts was her home. 

“I’ll be here waiting for you. Just wait; all the rumors will be over, and before you know it, the Daily Prophet will be reporting on the next big scandal. Believe me. Gossip never lasts for very long, especially in the wizarding world. Everything will be alright, my dear.” He murmured, resting his chin upon her head.

Her eyes welled with tears. "I miss him, Moony." 

"I know, my dear. I know."

Moments later, a warning whistle sounded; the students still bidding farewell to their families on the platform started hurrying onto the train - all but one.

“Quick, you’ll miss the train.” Said Lupin distractedly, ushering her towards the train. “Off you go.”

For a brief moment, Cassia took a final glance back at the lanky man before she disappeared onto the train.

“I love you!” Cassia called out of the open window as the train began to leave the station. The tall figure of her uncle shrank rapidly, then the train rounded a bend and, he was gone.

Picking up Artemisia’s cage in one hand and the handle of the trunk in the other, she darted off down the corridor. Cassia peered through the glass-paneled doors into the compartments of each one she passed, which all just so happened to be full. She couldn't help but notice that a lot of people stared back at her with great interest and that several even nudged their friends, pointing her out as she strolled past. 

After she'd met this same behavior with several carriages that she passed, Cassia began to remember the sole reason for her sudden fame. This outcome was exactly what she had hoped to avoid; after all, her photographs had been posted on every front page of the Daily Prophet all summer. It seemed as though her dreams of fading into the shadows would be less likely considering the circumstances. 

Upon her arrival to the very last carriage sat the twin brother of her dearest friend Matilda Bletchley.

Seeing no other option, Cassia slid the door open and tugged her trunk inside, greeting the boy with the dirty-blonde hair and permanent frown.

“Hi, Miles.” Cassia greeted. "Can I sit in here with you?" 

Miles Bletchley sat beside the window, refusing to look up from his latest copy of the Daily Prophet, seeming extremely uninterested in the arrival of his sister’s best friend. His dirty-blonde hair had fallen over his eyes, but from where Cassia stood, she could see that he still hadn’t strayed from the pages of his newspaper.

"Well, well, if it isn't Gryffindor's Princess." He smirked devilishly, referring to her current title given by Rita Skeeter in the Daily Prophet. "Oh please, do come in. I should be honored to be sharing a coach with a celebrity such as yourself. Looking for my sister, I presume?" 

Cassia placed Artemisia’s cage in the luggage rack and sat down, taking her place opposite The Slytherin boy, now wishing that she hadn’t.

“Yes, actually. Where might she be?” Cassia replied, slightly annoyed that he still would not meet her eyes.

Turning the page of the newspaper, Miles shrugged and replied with a simple. "With the rest of those perfect twats in the front carriage. I don't know why... Just a bunch of arse kissers and do-gooders... Maybe you should've been up there as well, princess. You would've fit in really well with that lot."

The train rattled onwards, speeding the students of Hogwarts further into the countryside. It was a rather bizarre sort of day; one minute, the carriage was full of sunlight, and the next, they were passing beneath ominously grey clouds. 

"Anything from the trolley dears?" Asked the Trolley Witch, sliding the compartment door open. 

Pink in the face, Cassia shook her head and muttered. "No, thank you. I'm not very hungry."

However, the sudden rumble from the pit of her stomach made Miles slump in his seat and groan loudly. "Hold on, hold on... A packet of droobles, two cauldron cakes, and a licorice wand... Actually, better make that three cakes. She's going to need it." 

Before Cassia had time to comprehend the current events, Miles had reached deep into the right pocket of his black slacks, his hand emerging seconds later with a hand full of gold coins. He hadn't even bothered to count it, just dropped them all into the Trolley Witch's palm as if the money didn't matter to him at all, which it probably didn't. Miles was, after all, the heir to the Bletchley Family Manor. 

Once the compartment door had closed, he tossed everything into her lap, leaving only the licorice wand to himself. 

"Thank you-."

"Don't thank me yet, princess. You owe me." He mumbled, returning his attention to the newspaper. 

Money had no significance to the Bletchley's, not when their family had more than enough to buy all of England twice over. In the back of her mind, Cassia knew that money would not satisfy the Slytherin boy. Nevertheless, she was indebted. 

At that precise moment, the door of their compartment slid open, revealing a gorgeous girl with long blonde hair and glowing skin. It was Tilly. 

"Cass!" Tilly greeted with a grin. "I've been so worried about you. Oh, it's so good to see you! How are you feeling? How was your summer? Are you alright? You look really pale. Miles! Does she look pale to you? Oh dear, you need to eat something. Miles! She needs to eat something. Have you eaten anything? Please tell me you've eaten something. What do you need? Do you need me to get you something to eat-." 

"Tilly!" Cassia cried, whilst a smirking Miles tried to contain his laughter. "I'm fine, I swear. You really don't have to worry." 

"Don't listen to her, fruitcake." Said Miles, chuckling at his twin sister. "Cassia's too nice to tell you to piss off. But I'm not, so... piss off."

"Piss off." Tilly mimicked, completely irked by her brother's interruption.

But soon, Tilly's attention had returned to her friend. During her outburst, Tilly had wondrously wrapped her slender arms around Cassia, squeezing her so tight that she hadn't any air left in her lungs. Although she could be quite overbearing at times, Cassia was grateful to have Tilly as a friend. 

"Are you sure you don't want to talk about what happened-."

"So!" Cassia interrupted, cutting the blonde off swiftly. "Miles was just telling me that you're a prefect this year? Congratulations, Tills."

Cassia hadn't anticipated that Tilly could be so easily distracted. However, it didn't take much effort before the bubbly blonde had jumped right onto the next subject. 

"Oh yes! Weasley and I. Well, there are two fifth-year prefects from each house, which is quite surprising, actually. I thought for sure that Granger would've been a prefect also, but I suppose not." Said Tilly as she released Cassia and took her seat beside her brother. 

For what seemed like hours, Tilly dragged on about her new role as a Gryffindor prefect whilst Miles, and Cassia sat rolling their eyes at one another. 

Glancing at the newspaper sat beside Miles, Cassia noticed something out of the corner of her which interested her greatly. Upside-down it had been hard to tell just what the picture on the front page was, but Cassia now realized that it was a fairly clear image of Amos Diggory. She barely recognized him, had it not been for the familiar sandy blonde hair, she would've been completely oblivious. 

But she knew that hair color. 

One of Amos' hands was clenched around a rather large bag of gold; the other hand holding close a photograph of his only child. The caption: Gone But Never Forgotten - The Short Life of Cedric Diggory. 

Beneath this were listed the titles of other articles inside. 

CORRUPTION IN THE QUIDDITCH LEAGUE: How The Tornados Are Taking Control. 

SECRETS OF THE ANCIENT RUINS REVEALED. 

SIRIUS BLACK: Villian or Victim? 

Cassia's heart skipped at the sight of the final title. She'd crossed her fingers and hoped that upon her return to Hogwarts, the articles would have stopped. Cassia finished reading and stared at the page in disbelief. But ever rereading the headline several times, she realized that it wasn't a dream. 

THE TRAGIC LOVE STORY: Cedric Diggory and Cassia McKinnon. 

**Notes for the Chapter:**

> For the Bletchley Twins, I've cast Jack Fenenga as Miles and Jessica Alexander as Matilda (Tilly)


End file.
